Condensed Consolidated Statements of Comprehensive Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Net Income (Loss) Attributable to Parent [Abstract]
Sales	$ 577	$ 534	$ 1,691	$ 1,537
Cost of sales	376	337	1,088	957
Gross profit	201	197	603	580
Selling, general and administrative expenses	110	102	328	294
Legacy and separation-related expenses, net	(3)	13	14	25
Equity and other income	(8)	(5)	(29)	(20)
Operating income	102	87	290	281
Net pension and other postretirement plan non-service income and remeasurement adjustments	(10)	(17)	(30)	(60)
Net interest and other financing expenses	15	10	45	28
Income before income taxes	97	94	275	313
Income tax expense	33	38	154	114
Net income	$ 64	$ 56	$ 121	$ 199
NET INCOME PER SHARE
Basic (usd per share)	$ 0.33	$ 0.27	$ 0.61	$ 0.97
Diluted (usd per share)	$ 0.33	$ 0.27	$ 0.61	$ 0.97
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
Basic (shares)	195	204	199	204
Diluted (shares)	196	204	200	204
Dividends paid per common share (usd per share)	$ 0.07	$ 0.05	$ 0.22	$ 0.15
COMPREHENSIVE INCOME
Net income	$ 64	$ 56	$ 121	$ 199
Other comprehensive (loss) income, net of tax
Unrealized translation (loss) gain	(13)	6	(9)	3
Amortization of pension and other postretirement plan prior service credit	(3)	(2)	(7)	(6)
Other comprehensive (loss) gain	(16)	4	(16)	(3)
Comprehensive income	$ 48	$ 60	$ 105	$ 196